passing by reference... my darkest enemy
actual reason below:
In your case (without reference) the compiler generates a temporary object (int) for the first argument of your MyApplication constructor. You pass this temporary int to QApplication’s constructor (with int reference), which saves the address of this reference. Once your MyApplication constructor is done the temporary int is destroyed but QApplication still has its address.
#if the headers are not installed, the newer apis won't be activated
#find which version of SDL we are building against
find_file(sdl_h SDL_version.h ${SDL_INCLUDE_DIR})
if(sdl_h)
file(STRINGS ${sdl_h} sdl_majorversion_tmp REGEX "SDL_MAJOR_VERSION[\t' ']+[0-9]+")
file(STRINGS ${sdl_h} sdl_minorversion_tmp REGEX "SDL_MINOR_VERSION[\t' ']+[0-9]+")
file(STRINGS ${sdl_h} sdl_patchversion_tmp REGEX "SDL_PATCHLEVEL[\t' ']+[0-9]+")
string(REGEX MATCH ".([0-9]+)" sdl_majorversion "${sdl_majorversion_tmp}")
string(REGEX MATCH ".([0-9]+)" sdl_minorversion "${sdl_minorversion_tmp}")
string(REGEX MATCH ".([0-9]+)" sdl_patchversion "${sdl_patchversion_tmp}")
math(EXPR sdl_version "${sdl_majorversion}*10000 + ${sdl_minorversion}*100 + ${sdl_patchversion}")
if(NOT (sdl_version LESS "010300"))
message(STATUS "Enabling SDL-1.3+ calls")
set(pascal_compiler_flags_cmn "-dSDL13" ${pascal_compiler_flags_cmn})
endif()
endif()
#find which version of SDL_mixer we have (for Mix_Init)
find_file(sdlmixer_h SDL_mixer.h ${SDLMIXER_INCLUDE_DIR})
if(sdlmixer_h)
file(STRINGS ${sdlmixer_h} sdlmixer_majorversion_tmp REGEX "SDL_MIXER_MAJOR_VERSION[\t' ']+[0-9]+")
file(STRINGS ${sdlmixer_h} sdlmixer_minorversion_tmp REGEX "SDL_MIXER_MINOR_VERSION[\t' ']+[0-9]+")
file(STRINGS ${sdlmixer_h} sdlmixer_patchversion_tmp REGEX "SDL_MIXER_PATCHLEVEL[\t' ']+[0-9]+")
string(REGEX MATCH ".([0-9]+)" sdlmixer_majorversion "${sdlmixer_majorversion_tmp}")
string(REGEX MATCH ".([0-9]+)" sdlmixer_minorversion "${sdlmixer_minorversion_tmp}")
string(REGEX MATCH ".([0-9]+)" sdlmixer_patchversion "${sdlmixer_patchversion_tmp}")
math(EXPR sdlmixer_version "${sdlmixer_majorversion}*10000 + ${sdlmixer_minorversion}*100 + ${sdlmixer_patchversion}")
if(sdlmixer_version GREATER "10209")
message(STATUS "Enabling enhanced SDL_Mixer calls")
set(pascal_compiler_flags_cmn "-dSDL_MIXER_NEWER" ${pascal_compiler_flags_cmn})
endif()
endif()
#find which version of SDL_image we have (for IMG_Init)
find_file(sdlimage_h SDL_image.h ${SDLIMAGE_INCLUDE_DIR})
if(sdlimage_h)
file(STRINGS ${sdlimage_h} sdlimage_majorversion_tmp REGEX "SDL_IMAGE_MAJOR_VERSION[\t' ']+[0-9]+")
file(STRINGS ${sdlimage_h} sdlimage_minorversion_tmp REGEX "SDL_IMAGE_MINOR_VERSION[\t' ']+[0-9]+")
file(STRINGS ${sdlimage_h} sdlimage_patchversion_tmp REGEX "SDL_IMAGE_PATCHLEVEL[\t' ']+[0-9]+")
string(REGEX MATCH ".([0-9]+)" sdlimage_majorversion "${sdlimage_majorversion_tmp}")
string(REGEX MATCH ".([0-9]+)" sdlimage_minorversion "${sdlimage_minorversion_tmp}")
string(REGEX MATCH ".([0-9]+)" sdlimage_patchversion "${sdlimage_patchversion_tmp}")
math(EXPR sdlimage_version "${sdlimage_majorversion}*10000 + ${sdlimage_minorversion}*100 + ${sdlimage_patchversion}")
if(sdlimage_version GREATER "010207")
message(STATUS "Enabling enhanced SDL_Image calls")
set(pascal_compiler_flags_cmn "-dSDL_IMAGE_NEWER" ${pascal_compiler_flags_cmn})
endif()
endif()